Anybody ever seen a 5A 250V single pole switch?

I just removed a switch in a 1940s house to replace it with a new one and the old one reads: 5A 250V on the top and then 10A 125V on the bottom. It's a single pole switch on a 15A circuit so I replaced it with a 15A rated single pole switch. I've just never run into anything like the original one. Has anyone ever seen something like this?

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Yes, most old switches where rated 10 A @120 V. Most of those switches were of the AC/DC type as opposed to the more modern T rated variety. T rated means that the contacts are rated to switch tungsten lighting loads. (ex., Incandescent lamps) When lamps with tungsten filaments are first turned on, there is a high inrush of current. This inrush supposedly eroded softer contacts and caused premature failure. Modern switches are rated at 15 A on up.

It is likely that, for this switch design, 5A @ 250v gives you the same contact life as 10A @ 125v.
The switch would be derated even more if it has to handle inductive loads or tungsten [incandescent lamps] load or DC current.

My Digi-Key paper catalog gives several of these ratings for some their switches.

Switching capacity : This is the amount of arcing the switch is designed to. It depends on materials of which the contacts are made and the speed at which they close

Load capacity : This is the amount of current a closed switch can have without overheating. It depends on the size of the contacts and the contact area between them

The current written on most household switches i have seen (large copper contacts with silvered ends) is usually load capacity and the switching capacity is up to 1.5 - 2 times higher

In modern miniature switches and in many very old switches (which use the friction plates design) the switching capacity is lower than the load capacity

The load capacity is not related to the voltage. If you have 5 A 250 V switch you may not load it above 5 A at 125 V

The switching capacity can be considered higher when using lower voltage (that makes shorter arcs). But i dont think much higher

Probably in this switch the limit is the switching capacity and thats why it has different ratings at different voltages

In many modern switches and contactors (relays) you often will see a huge amount of mismatching ratings written on all sides. They are there because of the difference between load and switching capacity

Further more - some countries allow the use of the switch at lower current or voltage because of larger safety factors in the code. In this case you will see the different rating written along witht the approval icon for that country

In most relays i have seen in Israel the written current is the load capacity for different classes of appliance. The classes are based on inrush current and in this way the rating reflects switching capacity too. There is a list of up to 4 different currents on the same device like :